title: Hydrogen peroxide content and pH of expired breath condensate from patients with asthma and COPD.
abstract: BACKGROUND
  Oxidative stress is implicated in the pathogenesis of asthma and chronic obstructive pulmonary disease (COPD). Analysis of the expired breath condensate (EBC) has been suggested to provide non-invasive inflammatory markers that reflect oxidative stress in the airways.
  
  
  OBJECTIVE
  The present study attempts to elucidate whether the hydrogen peroxide (H2O2) levels and pH values in EBC may be useful as biomarkers of the activity or severity of asthma and COPD.
  
  
  METHODS
  We measured the H2O2 levels and pH values using a derivatives of reactive oxygen metabolites exhalation test kit (Diacron) and a pH analyser, respectively, in EBC obtained using an EcoScreen from 29 patients with asthma, 33 with COPD, and 33 healthy individuals (all non-smokers). We then examined the relationships among oxidative stress and the asthma control test (ACT) or COPD assessment test (CAT) scores, pulmonary function, fractional exhaled nitric oxide (FeNO), and the extent of low attenuation areas on HRCT.
  
  
  RESULTS
  The H2O2 levels were elevated and pH was lower in both asthma (H2O2; 8.75 ± 0.88 μM, p < 0.01, pH; 7.14 ± 0.07, p < 0.05) and COPD (H2O2; 7.44 ± 0.89 μM, p < 0.01, pH; 6.87 ± 0.10, p < 0.01) compared with control subjects (H2O2; 3.42 ± 0.66 μM, pH; 7.35 ± 0.04). Neither the H2O2 levels nor pH correlated with the ACT scores and FeNO in asthma patients. Neither the H2O2 levels nor pH significantly correlated with the pulmonary function in asthma and COPD. However, the CAT scores significantly correlated with the H2O2 levels in patients with COPD (r = 0.52, p < 0.01).
  
  
  CONCLUSIONS
  These findings suggest that oxidative stress is involved in the pathogenesis of asthma and COPD and that the H2O2 levels in EBC might reflect the health status in COPD.
authors.affiliation: 1Department of Laboratory Medicine, Shinshu University School of Medicine , Matsumoto , Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Murata
authors.forename: Keisaku
authors.initials: K
authors.lastname: Fujimoto
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Kitaguchi
authors.forename: Toshimichi
authors.initials: T
authors.lastname: Horiuchi
authors.forename: Keishi
authors.initials: K
authors.lastname: Kubo
authors.forename: Takayuki
authors.initials: T
authors.lastname: Honda
mesh_terms: D000328:Adult; D000368:Aged; D001249:Asthma / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D015415:Biomarkers / Q000378:metabolism; D001944:Breath Tests; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008168:Lung / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism; D018384:Oxidative Stress; D029424:Pulmonary Disease, Chronic Obstructive / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D012129:Respiratory Function Tests; D014057:Tomography, X-Ray Computed
chemical_list: D015415:Biomarkers; D009569:Nitric Oxide; D006861:Hydrogen Peroxide